People are used to the feeling of torque from flywheel effect when the transmission shifts, so CVTs make it feel like there is less torque, and the "Rubber band effect" is the lack of that kick in the butt. It is a matter of perception, not an actual performance issue.

When you buy an automatic transmission and demand shift shock, you're saying you don't want to be involved in gear selection, but you do want to be jolted every time it happens.

Think about what that means for a second. All the unsettling feedback, none of the control. It's tantamount to buying a machine the sole purpose of which is to poke you with a stick at random intervals while you're blindfolded.

Maybe they could do the BMW trick of aural engine enhancement, and use the sound system to simulate distinct ratios? I wonder as well, if there is some wear reduction on some part of the CVT by having many small steps in ratio change vs. a truly continous ratio change?

I think it's a neat feature to have for those who like the feeling of shift points. I really could care less either way, as long as it's reliable then that's all that matters, CVTs are not performance transmissions to begin with.

Presuming that CVT reliability is good, and that they are perhaps lighter with fewer moving parts, etc, I think it's a great feature for those who want the sensation of gear changes. I like to feel the engine rev up through a gear, make a change, and then rev up again. It's part of how I'm programmed I guess.

But I don't feel the need to make those gear changes myself. My wife can't drive one anyway, and has no desire to, so why not give consumers like me a choice in how a CVT drives and feels? The great thing is it's ALL orchestrated with computer programming. You can have it feel like a CVT if you want to. I can have it feel like a traditional automatic if I want to. No change in parts.

More choice, more flexibility, more options...these are always good in my opinion.

People are used to the feeling of torque from flywheel effect when the transmission shifts, so CVTs make it feel like there is less torque, and the "Rubber band effect" is the lack of that kick in the butt. It is a matter of perception, not an actual performance issue.

I think a simulated stick and clutch pedal would sell well, fake not so much.

Seriously though, I am also baffled why anyone would want to feel the shifts. After reading all the comments in the manual transmission thread how it's and "old" and "inferior" technology, why would anyone still be stuck with the "old" and "inferior" concept of fixed ratio gears?

I think a simulated stick and clutch pedal would sell well, fake not so much.

Seriously though, I am also baffled why anyone would want to feel the shifts. After reading all the comments in the manual transmission thread how it's and "old" and "inferior" technology, why would anyone still be stuck with the "old" and "inferior" concept of fixed ratio gears?

An active stick to control the transmission cones might be interesting.Kind of like having Hydrostatic drive.

I think the Daff CVT of the 60's and 70's had the cones controlled by engine vacuum. I have driven them, they worked quite well.For maximum speed you had to back off on the throttle :-)

The point is that CVTs are increasingly replacing automatics altogether, and the customer has no choice but the CVT. The nice part about it is if they want the smooth feel of the CVT, they can have it. If they want the feel of a stepped transmission, they can have it. Flexibility is great.

How many shift points does it have? None going up, and six going down? 8 going up, and 9 going down? Not only that, but nothing says it has to be the same "ratio" at each point. It could decide to make a step this time and do a slide next time.

I think the rubber band effect would drive me nuts. Lately I've been wondering how people managed before lockup torque convertors. The two hundred rpm "rubber" effect I can hear when it's unlocked bugs me. I could imagine a 1,000rpm effect or more.

Then again, I prefer an engine to lug down and just torque its way out of something.

I am pretty sure I've asked this in the past, but never gotten a good answer: what would manual control of a CVT look like? On an automatic it's pretty easy: up/down manual selection of the fixed gear ratios. On a CVT, would it just be a slide switch? Seems like manually fixed ratios would be required on a CVT--otherwise, one could not have manual control.

The point is that CVTs are increasingly replacing automatics altogether, and the customer has no choice but the CVT. The nice part about it is if they want the smooth feel of the CVT, they can have it. If they want the feel of a stepped transmission, they can have it. Flexibility is great.

Increased choice is a good thing only if the additional options are worthwhile. If I could only have toast for breakfast, adding eggs to the menu would be a meaningful increase in choice. Adding cyanide tablets wouldn't be.

"The feel of a stepped transmission" is three things:

1. Shift shock2. Interruption in power delivery3. The engine falling in and out of the optimal RPM range for whatever you're trying to do

In other words, all bad things.

I put up with all of those things in my car because it's manual, which means my toleration buys me a measure of control that I couldn't get otherwise. What is the argument for putting up with -- let alone WANTING -- those bad things in an automatic?

So far, all people have said is that stepless transmissions make the car feel broken. Everyone seems to understand that they only feel that way because they're used to "the feel of a stepped transmission." In other words, it's just habit. Why is nobody thinking "maybe I should look at it differently?"

1. Shift shock2. Interruption in power delivery3. The engine falling in and out of the optimal RPM range for whatever you're trying to do

In other words, all bad things.

I do agree that they made the package less efficient. If efficiency is your only metric, then sure, they're all "bad".

Life isn't always so black-and-white. I like to hear the engine rev up "through the gears". I like to feel the engine as it climbs through its power curve. I like to listen to the change in tone as it steadily increases in speed. I like to be able to load the engine down in a gear and not have it flare up in speed if I know that the load is temporary (like climbing a short hill or momentarily increasing my speed).

Variable ratios are boring to me. They further isolate the driver from the actions, from the feel, of the powertrain. I don't want that isolation. I want to feel it work. I want to hear it work. I actually LIKE that about stepped transmissions. I don't have manual transmissions in our vehicles for a few reasons, but it doesn't mean that I want to miss that feeling, that sensation, of a good engine/transmission combo going about its business.

I fully know that variable ratios are more efficient. I fully know that variable ratios enable better performance. That doesn't matter to me. If getting that last 1/10th of an MPG or that last 1 MPH in the 1320 means having to put up with a limp-feeling powertrain all the time, then I don't want it.

I don't have a problem with the mechanicals of a CVT. I like simple. I like easy. As a CVT owner, I would want to have a "D" mode where it would do its thing just like any other CVT. If I'm shuttling co-workers to lunch, or if my wife is driving the car, or if I'm just in the mood for quiet and smooth, "D" works. But I also want an "M" mode with paddle shifters so that I can work it up and down "through the gears" if I want to hear and feel the powertrain work. CVTs don't hold the engine for engine braking down hills or for switching back and forth on twisty roads. Sometimes that's what I want to do. Some may not want that, and that's cool; "D" is for them. Including an "M" mode costs very little and adds a huge degree of flexibility while still using the same equipment.

About abnormal wear, I'd hope any self-respecting engineer would use some type of wear leveling logic in their pre-defined steps,ie alternating between say a 1.35 and a 1.28 (eg) 'virtual third gear' or whatever.

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C'mon guys. Shift shock? Whazzat? No modern automatic trans has any. Retarded timing and throttle reduction are precisely timed in many cars so you don't feel nuttin' unless you got your foot in it.

And the whole advantage of a slushbox, as well as the reason most of them are much quicker at the strip than their identical manual transmission variants, is there is NO interruption of the power delivery, none at all.

Moving cams has widened powerbands so far that many engines have a table flat torque curve, this pretty much means you are always in the 'optimal' rev range as well.

Next I am waiting to hear someone try again to tell us that CVT's have no wear in normal use!

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The point is that CVTs are increasingly replacing automatics altogether, and the customer has no choice but the CVT. The nice part about it is if they want the smooth feel of the CVT, they can have it. If they want the feel of a stepped transmission, they can have it. Flexibility is great.

I hear ya, but what about durability and longevity? As long as there's a market for Pickups and larger SUV's for people who tow, I think the "traditional automatic" transmission will be around until they can beef up the CVT. Which is probably one reason ZF is making 8 and 9 speed units and pushing for more gears.

Variable ratios are boring to me. They further isolate the driver from the actions, from the feel, of the powertrain. I don't want that isolation. I want to feel it work. I want to hear it work. I actually LIKE that about stepped transmissions. I don't have manual transmissions in our vehicles for a few reasons, but it doesn't mean that I want to miss that feeling, that sensation, of a good engine/transmission combo going about its business.

The stepless feeling with a CVT IS the sensation of an engine/transmission combo going about its business. You're no more isolated from that than you are from the workings of a normal automatic.

Originally Posted By: Hokiefyd

I don't have a problem with the mechanicals of a CVT. I like simple. I like easy. As a CVT owner, I would want to have a "D" mode where it would do its thing just like any other CVT. If I'm shuttling co-workers to lunch, or if my wife is driving the car, or if I'm just in the mood for quiet and smooth, "D" works. But I also want an "M" mode with paddle shifters so that I can work it up and down "through the gears" if I want to hear and feel the powertrain work.

Again, the steplessness IS the sound and feeling of the powertrain working. I'm still not sure what you're talking about here.

I dislike the feeling and sound of a CVT, too. But I dislike the feeling of automatics by definition, so...

Again, the steplessness IS the sound and feeling of the powertrain working.

It's really not. With a stepless transmission, you push the accelerator and the engine revs up to a point where the software believes the engine provides the best combination of power and efficiency, and it continually varies the ratios to keep the engine there. It drones. It's a constant HUMMMMMMMM as the car accelerates forward. Smooth for sure. But it sounds like a constant speed vacuum cleaner. Or a boat. Or a go kart with a centrifugal clutch. There's very little change in the way the powertrain sounds. I don't like that. It's boring; it's monotonous. It's drab. Stepped ratios provide different sounds and feels from the powertrain.

And then on the other hand, where you might WANT a constant engine speed (like to hold a gear through twisty corners), a conventional CVT without step control can't offer that. If you're on and off the throttle, that CVT is going to cycle the engine up and down and not keep the engine cooking where you want it to. CVTs offer no control; with a stepped transmission, automatic or otherwise, the driver has full control over the engine.

I like control over the engine, as apparently you do. Because of a foot injury my wife sustained years ago, a clutch pedal in our cars is out. What's the next best thing? The ability for me to control engine speed through ratio selection. Stepless CVTs don't offer that, and I'm not interested in them for that reason. Give me ratio control with a CVT, even if it's a separate "M" mode or something, and I'd be happy with it.

Don't get me wrong; I'm not promoting CVTs. I'm saying that if my only choice in "automatic" transmission in a vehicle is a CVT, then I would like the ability to control it to some degree. Paddle shifters would be fine.

In the CVTs I've driven to date, the driver has ZERO control over what's going on. At least with a stepped automatic, you can dictate engine speed through gear selection.

I still haven't heard of a good answer to my question: how would you have manual control over a CVT otherwise?

I'll take a stab at that one.

Essentially, in order to have a full control over a CVT transmission, you would need a sliding lever, sort of like a dimmer. The ends of the lever's movements would represent the highest and lowest gear ratios and everything in between would be dictated by lever position. The problem with this approach would be the need to constantly adjust the lever and the gas pedal position. Since there would be no gates, one would have to smoothly slide the lever back and forth to adjust the speed. That would be a major headache even for enthusiasts. This is why the stepped CVTs are being implemented for those wanting to have some sort of manual control.

Personally I think it's a great idea. Think about this: you could program it to have say 5% steps in "race" mode. In "fun" mode you could have say 10% steps while accelerating, and say 20% downshifts--that way, it accelerates reasonably well, loaf along in a high gear--then with a click or two be deeply geared for passing. Without having to hit down ten times.

Imagine that: with a bit of software work, you could have as many (or few) gears as you wanted. And then when you aren't in the mode, set it to CVT mode. And then change your mind next week and redo it.

Having driven a few of them, I am doubtful that anyone consulted a BSFC chart for the engines.

The Nissans either lug the engine too much or have it running at redline all the time.

Seems like it would be possible to program in the BSFC chart and have it set the RPM according to throttle input (ie - low throttle, I don't want to accelerate fast, medium throttle - put it where it has the most volumetric efficiency , full throttle - best torque ,horsepower).

Again, the steplessness IS the sound and feeling of the powertrain working.

It's really not. With a stepless transmission, you push the accelerator and the engine revs up to a point where the software believes the engine provides the best combination of power and efficiency, and it continually varies the ratios to keep the engine there. It drones. It's a constant HUMMMMMMMM as the car accelerates forward. Smooth for sure. But it sounds like a constant speed vacuum cleaner. Or a boat. Or a go kart with a centrifugal clutch. There's very little change in the way the powertrain sounds. I don't like that. It's boring; it's monotonous. It's drab. Stepped ratios provide different sounds and feels from the powertrain.

Do you just not like it, or do you really think it represents greater isolation? Those are two different ideas.

Originally Posted By: Hokiefyd

And then on the other hand, where you might WANT a constant engine speed (like to hold a gear through twisty corners), a conventional CVT without step control can't offer that. If you're on and off the throttle, that CVT is going to cycle the engine up and down and not keep the engine cooking where you want it to. CVTs offer no control; with a stepped transmission, automatic or otherwise, the driver has full control over the engine.

If we're comparing a CVT to an automatic WITHOUT manual gear selection, I don't see how a stepped transmission offers any non-trivial kind of additional control. With a CVT, you mash the gas and then wait for the revs to climb; with a stepped automatic, you mash the gas and then wait for a downshift. Either way, there are annoying delays and the possibility of hunting for the right ratio.

Originally Posted By: Hokiefyd

I like control over the engine, as apparently you do. Because of a foot injury my wife sustained years ago, a clutch pedal in our cars is out. What's the next best thing? The ability for me to control engine speed through ratio selection. Stepless CVTs don't offer that, and I'm not interested in them for that reason. Give me ratio control with a CVT, even if it's a separate "M" mode or something, and I'd be happy with it.

Why have a CVT at all, then? A decently programmed 8-speed automatic, let alone a DCT, would blow it away in the manual mode without giving up much efficiency.

Why have a CVT at all, then? A decently programmed 8-speed automatic, let alone a DCT, would blow it away in the manual mode without giving up much efficiency.

An EXCELLENT question!

From a systems reliability perspective, the more things that you put in series, versus parallel reduce reliability. e.g. if you are designing a pump train and need multiple pumps in series, and they are (say) 90% reliable (each), two pumps in series will be 81% reliable, three pumps 72 and on.

In the case of extra speeds in a tranny, if each has a similar failure rate, an 8 speed will be far less reliable than a 4 with the same components....from a packaging perspective, 8 has to have smaller componentry for carrying the torque loadings, clutches etc.

As evidenced, they can make multi speed autos as reliable as they need to be...but complexity has its own issues.

Don't get me wrong, I'm not a CVT die hard. Until a few weeks ago, I disliked the driving experience (Maxima had "stepped" programmed into sport, and a "manual"hold mode which I liked)...Industrially, I've had to babysit them over the decades, and would prefer not to use them.

Do you just not like it, or do you really think it represents greater isolation? Those are two different ideas.

I don't like it because, among other things, I feel more disconnected from the powertrain. I know that the engine is as connected to the wheels with a CVT compared with a stepped automatic. But the engine flaring that goes along with true stepless operation is something I don't like. I'd rather be able to load the engine down with a locked torque converter than have its speed rise.

If we're comparing a CVT to an automatic WITHOUT manual gear selection, I don't see how a stepped transmission offers any non-trivial kind of additional control.

Yes, I agree with this. Every automatic I've owned allows pretty much full control over the ratio selection. If all I have is "D" and nothing else, then I'm lost. Note my "lack of like" of the 8-speed in the rental Chrysler 300 I had. All you had with that silly electronic shifter was D and L. The vehicle offered the driver zero control over ratio selection. And as I said in another post, the programming was horrible as well...you either had to cane or idle it around for the shift schedule to not drive you batty.

I would drive a clutchless manual transmission. I don't mind shifting gears. In fact, I ENJOY shifting gears. The primary reason I don't have a clutch in my car is because of my wife's previous foot injury (we trade cars often enough that it'd present a problem if mine had a clutch).

Originally Posted By: d00df00d

Why have a CVT at all, then? A decently programmed 8-speed automatic, let alone a DCT, would blow it away in the manual mode without giving up much efficiency.

I agree completely. As I said to demarpaint earlier in this thread, I'm not advocating for CVTs here. I prefer conventional stepped transmissions. I'm advocating for manual control if the only available "automatic" transmission is a CVT.

Do you just not like it, or do you really think it represents greater isolation? Those are two different ideas.

I don't like it because, among other things, I feel more disconnected from the powertrain. I know that the engine is as connected to the wheels with a CVT compared with a stepped automatic. But the engine flaring that goes along with true stepless operation is something I don't like. I'd rather be able to load the engine down with a locked torque converter than have its speed rise.

It seems like your definition of "connected" mainly involves the side-effects of gear changes in a stepped transmission. That's not a definition I can make sense of, but if I accept it then I can see why you feel that CVTs "feel less connected." If that's not what you mean, then I have no idea what you mean.

Back on-point, I still don't see how there's any point to manually selectable ratios in a CVT. It seems to me that either you want a CVT, or you want a good stepped transmission...

It seems like your definition of "connected" mainly involves the side-effects of gear changes in a stepped transmission. That's not a definition I can make sense of, but if I accept it then I can see why you feel that CVTs "feel less connected." If that's not what you mean, then I have no idea what you mean.

Maybe I can explain it differently. With a stepless transmission, there is no consistent relationship between engine speed and road speed (unless you're really going fast and it's at the lowest point of its range). Take driving through the mountains or twisty corners. As you press the gas, the engine is quite free to spin up and down without any meaningful change in road speed. The engine usually spins up before the CVT starts reducing the ratio (that rubberband effect), so there's a point where you're wasting time spinning the engine up so that it can fall back down because of the tightening CVT belt.

You also can't hold the engine at a certain speed range with a CVT. Say you are driving on curvy roads and you want to hold the engine at 2500-3500 rpm for better response. With the automatics I own, I'd put them in "3" and drive 55 mph through the corners. I have engine braking going down hill, the engine is already set up for an uphill run, and I have a certain level of control over the car. Stepless operation means the engine might fall down to near idle when off the throttle, and might zing up past were it really needs to be to regain momentum. I drive CVTs every day at work (though they're in hybrids). They're fine for putzing around, but they don't suit a more aggressive style of driving at all.

I think I'm inter-mingling the terms "control" and "connectedness". To me, you can't have control without being connected to something, and being connected to something implies a certain level of control. I don't have ANY level of control over the engine with a stepless transmission, and I therefore feel disconnected from it.

Originally Posted By: d00df00d

Back on-point, I still don't see how there's any point to manually selectable ratios in a CVT. It seems to me that either you want a CVT, or you want a good stepped transmission...

I agree. As I said earlier, I don't WANT a CVT. I don't PREFER a CVT. I want a good stepped transmission. But if I'm forced into a CVT with a car purchase...if the only available automatic transmission is a CVT...then I want the ability to select ratios.

It seems like your definition of "connected" mainly involves the side-effects of gear changes in a stepped transmission. That's not a definition I can make sense of, but if I accept it then I can see why you feel that CVTs "feel less connected." If that's not what you mean, then I have no idea what you mean.

Maybe I can explain it differently. With a stepless transmission, there is no consistent relationship between engine speed and road speed (unless you're really going fast and it's at the lowest point of its range). Take driving through the mountains or twisty corners. As you press the gas, the engine is quite free to spin up and down without any meaningful change in road speed. The engine usually spins up before the CVT starts reducing the ratio (that rubberband effect), so there's a point where you're wasting time spinning the engine up so that it can fall back down because of the tightening CVT belt.

You also can't hold the engine at a certain speed range with a CVT. Say you are driving on curvy roads and you want to hold the engine at 2500-3500 rpm for better response. With the automatics I own, I'd put them in "3" and drive 55 mph through the corners. I have engine braking going down hill, the engine is already set up for an uphill run, and I have a certain level of control over the car. Stepless operation means the engine might fall down to near idle when off the throttle, and might zing up past were it really needs to be to regain momentum. I drive CVTs every day at work (though they're in hybrids). They're fine for putzing around, but they don't suit a more aggressive style of driving at all.

I think I'm inter-mingling the terms "control" and "connectedness". To me, you can't have control without being connected to something, and being connected to something implies a certain level of control. I don't have ANY level of control over the engine with a stepless transmission, and I therefore feel disconnected from it.

I see what you're saying.

You're used to linking engine RPM with speed. A CVT links engine RPM with acceleration. There's still a connection; it's just to somthing else.

Regarding the delays on throttle tip-in, you pretty much described what I dislike about all automatics. It plays out slightly differently, but isn't the effect generally the same?

On gear/ratio holds and engine braking, you're completely right. This is largely a matter of programming. I remember reading that some Subarus are starting to use their CVTs to engine brake. It should be solvable in the near future, as should the delays as the hardware gets better.

Completely agree that control and connectedness are related.

This is mainly an academic discussion for me as well, as only an injury like what you described would get me to drive anything but stick.

The first time I ever drove a CVT-equipped rental car, I was shocked that under hard acceleration it doesn't just hold engine speed at the torque peak at first, then gradually ramp down the ratio as more power is needed. I wondered why any OEM would go to the trouble of developing a CVT, only to make it mimic a geared automatic.

Then I remembered that 95% of car buyers probably don't even know what a CVT is, let alone what the real advantages are (or what they should be).

You're used to linking engine RPM with speed. A CVT links engine RPM with acceleration. There's still a connection; it's just to somthing else.

Correct, and an excellent observation.

Originally Posted By: d00df00d

Regarding the delays on throttle tip-in, you pretty much described what I dislike about all automatics. It plays out slightly differently, but isn't the effect generally the same?

Sometimes, and to some degree. If the torque converter is unlocked, there will be some engine speed flare. In the automatics I've owned, though, a lower gear selection still keeps the engine percolating at a speed where I like it, so it seems to find that "fluid connection" faster. Like you correctly observed, a stepped transmission links engine speed with road speed, so throttle tip-in quickly resumes the engine to its correct road speed equivalent, even if there is some extra speed flare due to an unlocked torque converter. The CVT must match engine speed to how fast it thinks I want to accelerate, and that seems to contribute to that rubberband effect.

Yep, people are stupid. I've seen too many posts on various forums about "slipping" CVT. Dealers saw a lot of that too and the car makers decided to dumb it down to the lowest common denominator. Welcome to the future, LOL.

Yes. This is an excellent example of correct programming. If the things works well and shows promise enthusiasts will embrace it. Note that in that thread there are folks confused about throttle programming issues. Most folks just don't get how important these things are, even more so than hardware IMO.

I'll be very interested in how it responds to engine mods for more power and tuning mods that reduce torque management...

Edited by SteveSRT8 (07/20/1410:30 AM)

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